A terthiophene derivative, a preparation method and application thereof, an electrochromic film and a preparation method thereof

Abstract

The present invention relates to the technical field of electrochromic thin films, and in particular to a terthiophene derivative and a preparation method and application thereof, as well as an electrochromic thin film and a preparation method thereof. In the present invention, 5,5"-dibromo-2,2':5,2"-terthiophene, tributyl(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)stannane, a catalyst and a solvent are mixed under a protective atmosphere, and a reaction is performed to obtain a terthiophene derivative. The derivative can be applied to an electrochromic thin film; the present invention successfully prepares an electrochromic thin film that is purple in a neutral state, transparent in an oxidized state, can change color at a voltage of 0.3 to 0.7V, has a fast response time, high optical contrast and good stability by electrochemically polymerizing the terthiophene derivative.

Description

Technical Field

[0001] The present invention relates to the technical field of electrochromic thin films, and particularly to a terthiophene derivative, a preparation method and application thereof, and an electrochromic thin film and a preparation method thereof. Background Art

[0002] Electrochromism refers to the phenomenon that, under the action of an external voltage, a material undergoes an oxidation-reduction reaction due to the injection and extraction of charges, accompanied by the doping and dedoping of electrolyte ions, resulting in a change in its optical absorption in the visible-near infrared region, and macroscopically showing a reversible change in color and transmittance. Early electrochromic materials were mainly inorganic electrochromic materials. However, conductive polymers are considered to be the most promising new generation of materials because they have the advantages of easy structural modification, easy film-forming processing, flexibility, and good oxidation-reduction properties. They have been widely studied and rapidly developed in the past few decades. Among many conductive polymer electrochromic materials, organic conjugated polymers have attracted extensive attention from researchers due to their excellent coloring efficiency, high optical contrast, fast switching time, and adjustable color.

[0003] The RGB trichromatic model includes almost all colors that can be perceived by human vision and is one of the most widely used color systems. Display technology requires materials to be able to switch between primary colors and transparency. However, there are still few electrochromic thin films that can switch between purple and transparency. Therefore, providing a high-performance monomer for electrochromic thin films to enable electrochromic thin films to switch between purple and transparency is a technical problem that needs to be urgently solved by those skilled in the art. Summary of the Invention

[0004] The purpose of the present invention is to provide a terthiophene derivative, a preparation method and application thereof, and an electrochromic thin film and a preparation method thereof to solve the problems existing in the prior art.

[0005] To achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0006] The present invention provides a terthiophene derivative having the following structure:

[0007]

[0008] The present invention also provides a preparation method of the above terthiophene derivative, including the following steps:

[0009] Under a protective atmosphere, 5,5”-dibromo-2,2’:5,2”-terthiophene, tributyl(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)stannane, a catalyst and a solvent are mixed and reacted to obtain the terthiophene derivative.

[0010] Preferably, the protective atmosphere contains nitrogen or argon;

[0011] The catalyst contains Pd(PPh3)4, Pd(OAc)2 or Pd(PPh3)2Cl2;

[0012] The solvent contains N,N-dimethylformamide or 1,4-dioxane.

[0013] Preferably, the molar ratio of tributyl(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)stannane to 5,5”-dibromo-2,2’:5,2”-terthiophene is 2.5-3.5:1;

[0014] The dosage ratio of the solvent to 5,5”-dibromo-2,2’:5,2”-terthiophene is 20-40 mL:1 mmol;

[0015] The molar ratio of the catalyst to 5,5”-dibromo-2,2’:5,2”-terthiophene is 0.03-0.1:1.

[0016] Preferably, the reaction temperature is 150-160 °C and the time is 16-20 h.

[0017] The present invention also provides the application of the above-mentioned terthiophene derivative in an electrochromic film.

[0018] The present invention also provides an electrochromic film, and the polymerization monomer of the electrochromic film is the above-mentioned terthiophene derivative.

[0019] The present invention also provides a preparation method of the above-mentioned electrochromic film, comprising the following steps:

[0020] Adding the terthiophene derivative and tetrabutylammonium hexafluorophosphate into an electrolytic solvent, and performing electrochemical polymerization to obtain an electrochromic film.

[0021] Preferably, the dosage ratio of the terthiophene derivative to the electrolytic solvent is 0.5-1.5 mmol:1 L;

[0022] The dosage ratio of the tetrabutylammonium hexafluorophosphate to the electrolytic solvent is 0.09-0.12 mol:1 L;

[0023] The electrolytic solvent contains dichloromethane and acetonitrile; the volume ratio of dichloromethane to acetonitrile is 6-10:1-3.

[0024] Preferably, the polymerization voltage of the electrochemical polymerization is -0.3-0.9 V and the scanning speed is 50-120 mV / s.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention uses terthiophene as the central core and EDOT as the electrochromic group to prepare a pure D-type monomer E3TE (i.e., a terthiophene derivative) with a medium band gap, and successfully prepares a high-performance purple-transparent electrochromic film by cyclic voltammetry; this film can achieve color change at a voltage of -0.3 to 0.7 V, with an optical contrast of 25% in the wavelength range of 575 nm, a coloring time of 0.4 s, and a fading time of 0.26 s; in the wavelength range of 900 nm, the optical contrast is 25.79%, the coloring time is 0.56 s, and the fading time is 0.59 s; due to the longer average conjugation length brought by the higher degree of polymerization, its optical contrast basically does not decay after 600 cycles, and it is a new type of high-performance electrochromic material with great potential for purple-transparency. Brief Description of the Drawings

[0027] Figure 1 It is the cyclic voltammetry polymerization curve graph of the terthiophene derivative prepared in Example 1 of the present invention;

[0028] Figure 2 It is the ultraviolet-visible absorption spectrum graph of the electrochromic film prepared in Example 1 of the present invention under different voltages;

[0029] Figure 3 It is the response time graph of the electrochromic film prepared in Example 1 of the present invention in the 575 nm band;

[0030] Figure 4 It is the response time graph of the electrochromic film prepared in Example 1 of the present invention in the 900 nm band;

[0031] Figure 5 It is the kinetic test graph of the electrochromic film prepared in Example 1 of the present invention in the 575 nm band;

[0032] Figure 6 It is the kinetic test graph of the electrochromic film prepared in Example 1 of the present invention in the 900 nm band. Detailed Description of the Invention

[0033] The present invention provides a terthiophene derivative with the following structure:

[0034]

[0035] The present invention also provides a preparation method of the above terthiophene derivative, including the following steps:

[0036] Under a protective atmosphere, 5,5”-dibromo-2,2’:5,2”-terthiophene, tributyl(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)stannane, a catalyst and a solvent are mixed and reacted to obtain a terthiophene derivative.

[0037] In the present invention, the protective atmosphere contains nitrogen or argon, preferably nitrogen;

[0038] The catalyst contains Pd(PPh3)4, Pd(OAc)2 or Pd(PPh3)2Cl2, preferably Pd(PPh3)4;

[0039] The solvent contains N,N-dimethylformamide or 1,4-dioxane, preferably N,N-dimethylformamide.

[0040] In the present invention, the structure of 5,5”-dibromo-2,2’:5,2”-terthiophene is as follows:

[0041]

[0042] The structure of tributyl(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)stannane is as follows:

[0043]

[0044] In the present invention, the molar ratio of tributyl(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)stannane to 5,5”-dibromo-2,2’:5,2”-terthiophene is 2.5 - 3.5:1, preferably 2.8 - 3.3:1, more preferably 2.9 - 3.2:1;

[0045] The dosage ratio of the solvent to 5,5”-dibromo-2,2’:5,2”-terthiophene is 20 - 40 mL:1 mmol, preferably 25 - 35 mL:1 mmol, further preferably 26 - 34 mL:1 mmol, more preferably 28 - 32 mL:1 mmol;

[0046] The molar ratio of the catalyst to 5,5”-dibromo-2,2’:5,2”-terthiophene is 0.03 - 0.1:1, preferably 0.04 - 0.07:1, further preferably 0.05:1.

[0047] In the present invention, 5,5”-dibromo-2,2’:5,2”-terthiophene, tributyl(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)stannane, a catalyst and a solvent are mixed and heated to reflux, and the reaction is carried out under the reflux state.

[0048] In the present invention, the reaction temperature is 150 to 160 °C, preferably 153 to 157 °C, and more preferably 155 °C; the time is 16 to 20 h, preferably 17 to 18 h, and more preferably 17.4 to 17.6 h.

[0049] In the present invention, after the reaction is completed, the reaction mixture is extracted with dichloromethane, washed three times with saturated brine, the organic phases are combined and dried over anhydrous Na2SO4, and the organic phase is purified by column chromatography to obtain the target product 5,5”-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-2,2':5',2”'-terthiophene, i.e., the terthiophene derivative.

[0050] The present invention also provides the application of the above terthiophene derivative in an electrochromic film.

[0051] The present invention also provides an electrochromic film, and the polymerization monomer of the electrochromic film is the above terthiophene derivative.

[0052] The present invention also provides a preparation method of the above electrochromic film, including the following steps:

[0053] The terthiophene derivative and tetrabutylammonium hexafluorophosphate are added to an electrolytic solvent for electrochemical polymerization to obtain an electrochromic film.

[0054] In the present invention, the dosage ratio of the terthiophene derivative to the electrolytic solvent is 0.5 to 1.5 mmol: 1 L, preferably 0.8 to 1.2 mmol: 1 L, and more preferably 0.9 to 1.1 mmol: 1 L;

[0055] The dosage ratio of the tetrabutylammonium hexafluorophosphate to the electrolytic solvent is 0.09 to 0.12 mol: 1 L, preferably 0.1 to 0.11 mol: 1 L, and more preferably 0.104 to 0.106 mol: 1 L;

[0056] The electrolytic solvent contains dichloromethane and acetonitrile; the volume ratio of dichloromethane to acetonitrile is 6 to 10: 1 to 3, preferably 7 to 9: 1.5 to 2.5, and more preferably 8: 2.

[0057] In the present invention, the polymerization voltage of the electrochemical polymerization is -0.3 to 0.9 V, preferably 0.2 to 0.8 V, more preferably 0.3 to 0.7 V, and even more preferably 0.4 to 0.6 V; the scanning speed is 50 to 120 mV / s, preferably 80 to 110 mV / s, and more preferably 100 mV / s.

[0058] In the present invention, after the electrochemical polymerization is completed, a mixed cleaning agent is used for cleaning to remove the monomers or oligomers that have not undergone polymerization and the residual electrolyte on the film surface, and then it is naturally dried in air for standby. The mixed cleaning agent contains dichloromethane and acetonitrile; the volume ratio of dichloromethane to acetonitrile is 6-10:1-3, preferably 7-9:1.5-2.5, and further preferably 8:2.

[0059] The technical solutions provided by the present invention will be described in detail below in conjunction with the embodiments, but they cannot be construed as limiting the protection scope of the present invention.

[0060] Example 1

[0061] Weigh 5,5”-dibromo-2,2’:5,2”-terthiophene (0.41 g, 1 mmol), tributyl(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)stannane (1.29 g, 3 mmol) and 0.05 mmol of Pd(PPh3)4 and add them to a 100 mL two-necked round-bottom flask. Under nitrogen protection, add 20 mL of ultra-dry DMF solution, heat and reflux at 155 °C for 18 h, and cool to room temperature. Extract the reaction mixture with dichloromethane and wash it three times with saturated brine. Combine the organic layers, dry them with anhydrous Na2SO4, add an appropriate amount of silica gel with 200-300 mesh, and concentrate and mix the sample under vacuum. Using dichloromethane / petroleum ether (volume ratio 1:1) as the eluent and silica gel with 300-400 mesh as the stationary phase, perform column chromatography to obtain an orange solid, namely the terthiophene derivative (0.53 g, yield 80%). Its 1H NMR characterization is as follows: 1HNMR(600MHz,CDCl3)δ7.12(d,J = 3.8Hz,2H),7.10(d,J = 7.6Hz,2H),7.08(d,J = 3.8Hz,2H),6.41(s,2H),3.92(s,4H),3.80(s,4H).

[0062] The synthesis process of the terthiophene derivative is as follows:

[0063]

[0064] Add the terthiophene derivative prepared in this example (5.28 mg, 0.01 mmol), tetrabutylammonium hexafluorophosphate (0.387 g, 1 mmol), and 10 mL of electrolysis solvent to a 10 mL volumetric flask. The electrolysis solvent is a mixed solvent of dichloromethane and acetonitrile (V / V = 8:2). Ultrasonic for 5 min, and after complete dissolution, perform electrochemical polymerization. Using an ITO glass (0.9*4 cm) as the working electrode, a platinum wire as the counter electrode, and an Ag / AgCl electrode as the reference electrode, perform film formation by cyclic voltammetry, with a voltage range of -0.3 to 0.9 V and a scanning speed of 100 mV / s. Its polymerization curve is asFigure 1 As shown, from Figure 1 it can be seen that the peak current is continuously increasing, indicating that the monomer has undergone electro-polymerization and adhered well to the surface of the ITO conductive glass; after the electro-polymerization is completed, the film is washed in a mixed cleaning agent of dichloromethane and acetonitrile (V / V = 8:2) to remove the unpolymerized monomers or oligomers and residual electrolytes on the film surface, and then naturally dried in air for standby.

[0065] Test example

[0066] 0.387 g of tetrabutylammonium hexafluorophosphate was added to a 10 mL volumetric flask and made up to the mark with 8 mL of dichloromethane and 2 mL of acetonitrile, which was used as the blank solution. The ITO glass with a polymer film on its surface was used as the working electrode, a platinum wire as the counter electrode, and an Ag / AgCl electrode as the reference electrode, and was used in combination with a UV-visible spectrophotometer for electrochromic performance testing. The UV-visible absorption spectra of the electrochromic film at different voltages are as Figure 2 shown, from Figure 2 it can be seen that the prepared film can achieve color change at voltages of -0.3 to 0.7 V;

[0067] The response of the electrochromic film at the 575 nm band is as Figure 3 shown, from Figure 3 it can be seen that the coloring time of the film in the 575 nm wavelength range is 0.4 s and the fading time is 0.26 s.

[0068] The response time of the electrochromic film at the 900 nm band is as Figure 4 shown, from Figure 4 it can be seen that the coloring time of the film in the 900 nm wavelength range is 0.56 s and the fading time is 0.59 s.

[0069] The kinetic test of the electrochromic film at the 575 nm band is as Figure 5 shown, from Figure 5 it can be seen that the optical contrast of the film in the 575 nm wavelength range is 25%.

[0070] The kinetic test of the electrochromic film at the 900 nm band is as Figure 6 shown, from Figure 6 it can be seen that the optical contrast of the film in the 900 nm wavelength range is 25.79%.

[0071] Moreover, due to the longer average conjugation length brought about by the higher degree of polymerization, its optical contrast basically does not decay after 600 cycles, and it is a new type of high-performance electrochromic material with great potential for purple-to-transparent.

[0072] Example 2

[0073] Weigh 5,5"-dibromo-2,2':5,2"-terthiophene (0.41 g, 1 mmol), tributyl(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)stannane (1.08 g, 2.5 mmol) and 0.1 mmol of Pd(PPh3)4 into a 50 mL two-necked round-bottom flask. Under argon protection, add 30 mL of anhydrous and oxygen-free 1,4-dioxane solution, heat under reflux at 105°C for 24 h, and cool to room temperature. Extract the reaction mixture with dichloromethane and wash three times with saturated brine. Combine the organic layers and dry them with anhydrous Na2SO4. Add an appropriate amount of 200-300 mesh silica gel and concentrate and mix the samples under vacuum. Using dichloromethane / petroleum ether (volume ratio 1:2) as eluent and 300-400 mesh fine silica gel as stationary phase, chromatography was performed to obtain an orange-yellow solid, namely, a terthiophene derivative.

[0074] The terthiophene derivative (11.62 mg, 0.022 mmol) and tetrabutylammonium hexafluorophosphate (0.851 g, 2.2 mmol) prepared in this example were added to a 20 mL volumetric flask. The electrolytic solvent was a mixed solvent of dichloromethane and acetonitrile (V / V=7:3). Ultrasonication for 5 min, after complete dissolution, electrochemical polymerization was performed. Using an ITO / PET conductive substrate (2.5*4 cm) as the working electrode, a platinum sheet as the counter electrode, and an Ag / AgCl electrode as the reference electrode, the film was polymerized using cyclic voltammetry with a voltage range of -0.3 to 0.9 V and a scanning speed of 50 mV / s. The film was cleaned in a mixed cleaning agent of dichloromethane and acetonitrile (V / V=7:3) to remove the unpolymerized monomers or oligomers on the surface of the film and the residual electrolyte, and then dried naturally in air to obtain an electrochromic film.

[0075] As can be seen from the above examples, the present invention uses terthiophene as the central core and EDOT as the electrochromic group to prepare a pure D-type terthiophene derivative with a medium band gap, and successfully prepares a high-performance purple-transparent electrochromic film by cyclic voltammetry. Because the prepared polymer has a medium band gap, the prepared film is purple in the neutral state and transparent in the oxidized state; it can change color at a voltage of -0.3 to 0.7V, and has a high optical contrast and a fast response speed; thanks to the longer average conjugation length brought by the higher degree of polymerization, the optical contrast is basically not attenuated after 600 cycles, and the stability is excellent. It is a new type of purple-transparent high-performance electrochromic material with great potential.

[0076] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. Application of a terthiophene derivative in an electrochromic film, characterized in that, The preparation method of the electrochromic film comprises the following steps: Adding a terthiophene derivative and tetrabutylammonium hexafluorophosphate into an electrolytic solvent, and performing electrochemical polymerization to obtain an electrochromic film; The terthiophene derivative is ; The dosage ratio of the terthiophene derivative to the electrolytic solvent is 0.5~1.5 mmol: 1 L; The dosage ratio of the tetrabutylammonium hexafluorophosphate to the electrolytic solvent is 0.09~0.12 mol: 1 L; The electrolytic solvent comprises dichloromethane and acetonitrile; the volume ratio of the dichloromethane to the acetonitrile is 6~10: 1~3; The polymerization voltage of the electrochemical polymerization is -0.3~0.9 V, and the scanning speed is 50~120 mV / s.

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